Science Explains How Air in This Frat House Registered on a Breathalyzer

There was so much booze even the house got drunk.

Booze always flows more readily than usual during the holidays, but at a recent frat party in Maryland there was so much alcohol around that it got the house drunk. Local Baltimore news agency WJZ reported on Thursday that the air in the house during the party registered a .01 on breathalyzers carried by police who were trying to break up the party.

A blood alcohol concentration (BAC) of .01 is not super high — in the United States, the BAC for driving is .08 — but for it to accumulate to that level in the total volume of air in a house means that the concentration of alcohol in the humans breathing all that alcohol out must have been much, much higher.

The reason breathalyzers work in the first place is that alcohol doesn’t stay in the bloodstream once it’s consumed. Some of it (an estimated 20 percent) enters the bloodstream directly and rushes to the brain, and some of it gets into the general circulation via the blood vessels in the gut and the small intestine. Once it’s swirling around your system, some of that alcohol inevitably ends up in the blood vessels that supply your lungs, which, one hopes, continue to suck in and expel air as you drink.

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There, where the blood vessels lining the lungs meet the air you’re breathing in, a small exchange takes place: the blood vessels take in oxygen from the world outside and, in return, offers the alcohol molecules that evaporate out of the blood. Scientists have established that this exchange always happens at a constant rate, described by Henry’s Law. What this means is that, at any given moment during a drinking session, a cop can use a breathalyzer on your breath to measure the amount of alcohol in your blood because those numbers will always be proportional to each other.

Back to the frat house: There were about 70 people there, according to police estimates (many of whom were underage, which is why the cops stuck around for so long in the first place). We also know that everyone there was breathing out alcohol through their lungs at a constant rate, and that, together, they were breathing out enough alcohol into the air that it registered on a breathalyzer. The real question here is: how much alcohol needs to be in the air in order to register a .01?

In order to blow a .01 on a breathalyzer, the average person needs to consume about 0.75 oz of liquor. If we expand that to a 2,000-square-foot house with, say, 9-foot ceilings, you’d need … wait for it … 1.2 GALLONS OF LIQUOR IN THE AIR!

The reason the air doesn’t normally register in normal breathalyzer situations is that those usually involve a healthy amount of air flow (say, from a car window as a police officer peers into your car), which dilutes all the alcohol that’s being exhaled. But the frat house was a special case: According to WJZ, the brilliant inhabitants had taped garbage bags over the windows and insulated them as well, creating a fairly tight seal that kept all that precious alcohol inside.